1. Field of the Invention
The present invention relates generally to a hermetic compressor, and more particularly, to a cylinder assembly having the structure improved for easy suction of refrigerant into a cylinder, and a hermetic compressor having the cylinder assembly.
2. Background of the Related Art
As is known to those skilled in the art, a conventional hermetic compressor comprises a casing 100, a drive unit 200 disposed inside the casing 100, a compression unit 300, and a cylinder assembly 400, as shown in FIG. 1.
The casing 100 is comprised of an upper casing 110 and a lower casing 120 attached to each other, as shown, and has an inlet tube 130 and a discharge tube 140. Lubricant is stored at the bottom of the lower casing 120 and refrigerant flows in through the inlet tube 130 to be charged inside the casing 100.
The drive unit 200 comprises a stator 210 fixed in the casing 100, a rotor 220 disposed inside the stator to rotate relative thereto, and a crank shaft 230 disposed to rotate together with the rotor 220.
The compression unit 300 comprises a connecting rod 310 connected with an eccentric portion 240 of the crank shaft 230 being capable of converting the rotary movement of the rotor 220 into linear reciprocation, and a piston 320 connected with one end of the connecting rod 310.
The cylinder assembly 400 shown in exploded detail in FIG. 2 comprises a cylinder block 420 defining a cylindrical volume or cylinder 410 in which the piston is inserted, a cylinder head 430 connected with the cylinder block 420 by bolts A for sealing the cylinder 410, and a valve plate 440 interposed between the cylinder block 420 and the cylinder head 430.
Referring now to both FIGS. 1 and 2, the cylinder head 430 has a wall 431 formed at an inner side. The wall 431 divides the inside of the cylinder head 430 into a suction chamber 432 and a discharge chamber 433. The cylinder head 430 has a refrigerant path 434 and refrigerant from a suction muffler 500 flows into the suction chamber 432 through the refrigerant path 434.
A gasket 450 is interposed between the cylinder head 430 and the valve plate 440 for sealing therebetween.
The valve plate 440 comprises a suction port 441 and a discharge port 442. The suction port 441 connects the suction chamber 432 and the cylinder 410, and the discharge port 442 connects the discharge chamber 433 and the cylinder 410.
The suction port 441 is opened and closed by a suction valve 471. The suction valve 471 is integrally formed with a suction valve sheet 470 interposed between the cylinder block 420 and the valve plate 440. A gasket 460 is interposed between the suction valve sheet 470 and the cylinder block 420 for sealing therebetween.
The discharge port 442 is opened or closed by the movement of a discharge valve 481. The discharge valve 481 together with a stopper 482 and a keeper 483 are disposed in a recess 480, which is formed in the valve plate 440.
As shown in FIG. 3, in the conventional cylinder assembly 400 structured as described above, the pressure of the cylinder 410 is lower than that of the suction chamber 432 when the piston 320 moves from the top dead end to the bottom dead end, and the suction valve 471 moves in accordance with the pressure difference and thereby opens the suction port 441. Then, the refrigerant in the casing 100 flows into a suction muffler 500 (FIG. 1), and the refrigerant of the suction muffler 500 is sucked inside the cylinder 410 through the suction port 441 after passing the suction chamber 432.
However, in the case of a conventional cylinder assembly as described above, refrigerant is not easily sucked into the cylinder 410 because only the refrigerant inside the suction muffler 500 is sucked through the refrigerant path 434 at the time of the suction stroke of the piston 320.
In addition, since there is a large gap in pressure between the cylinder 410 and the suction chamber 432, the parts comprising the compressor are likely to undergo stress and the strength and starting efficiency of the compressor decrease.
An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
Accordingly, one object of the present invention is to solve the foregoing problems by providing a cylinder assembly having improved strength and starting efficiency and a hermetic compressor employing the same by permitting the refrigerant to be more easily sucked into the cylinder.
In order to achieve the above object of the present invention, the cylinder assembly comprises a cylinder block having a cylinder for compressing refrigerant, a valve plate contacted to one side of the cylinder block and having a suction port for sucking refrigerant into the cylinder, a suction valve for opening and closing the suction port, a cylinder head connected with the valve plate and having a suction chamber, a refrigerant path formed at one side of the cylinder head for letting refrigerant flow into the suction chamber, and a groove formed on the valve plate removed from the refrigerant path for guiding refrigerant into the suction chamber.
It is preferable that the groove extended from one edge of the valve plate to the suction chamber.
In addition, the hermetic compressor according to the present invention comprises a casing into which refrigerant can flow, a rotor rotatably inserted in a stator disposed inside the casing, a crank shaft rotated by the rotor, a connecting rod having one end connected with the crank shaft, a piston connected with another end of the connecting rod, and a cylinder assembly in which refrigerant is compressed by operation of the piston, and the cylinder assembly comprises a cylinder block having a cylinder for compressing refrigerant, a valve plate contacted to one side of the cylinder block and having a suction port for sucking refrigerant into the cylinder and a discharge port for discharging the compressed refrigerant from the cylinder, a suction valve for opening and closing the suction port, a discharge valve for opening and closing the discharge port, a cylinder head disposed at one side of the valve plate and having a suction chamber and a discharge chamber, a refrigerant path formed at one side of the cylinder head for letting refrigerant flow into the suction chamber, and a groove formed on the valve plate removed from the refrigerant path for guiding refrigerant inside the casing into the suction chamber.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the specification and drawings or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.